Fine Pointing and Tracking Onboard System for CubeSat Optical Satcom

Satellite data transmissions are complex due to the various factors that intervene in them. Many institutions have opted for laser communications in search of high data transmission rates, reduced size and weight, lower costs, and low power consumption, unlike radio-frequency communications. However, optical links require tremendously precise pointing and tracking since poor pointing can yield connection errors. Thus, fine pointing is required, with the ability to redirect the transceptor with exceptionally delicate motions, allowing a stable link within the sight window. In this work, the development of a pointing, acquisition, and tracking subsystem consisting of a computer vision system is presented, capable of recognising and detecting a guide beam emitted by an optical ground station, together with a fuzzy logic controller for servomotors to perform the tracking phase. The fine-pointing system was implemented on a printed circuit board for a trouble-free and adequate interface to communicate with any microprocessor. The outcome shows that the system can follow and identify the indicated beam amongst many other light sources at short and long distances. Likewise, the pointing accuracy was found to be within the same order of magnitude as the minimum required, showing that an onboard active tracking system for laser communications within a CubeSat is feasible. Ultimately, this research serves as an alternative method for the future development of affordable narrow-beam tracking systems for nanosatellite applications.